Crack Propagation in Freshwater and Saline Ice

1999 ◽  
Vol 578 ◽  
Author(s):  
Patrick J. Donovan ◽  
Masahiko Arakawa ◽  
Victor Petrenko
Keyword(s):  
Crack Propagation ◽  
Crack Velocity ◽  
High Speed ◽  
Acoustic Emissions ◽  
Crack Tip ◽  
High Speed Photography ◽  
Propagation Time ◽  
Reliable Technique ◽  
Resistance Method ◽  
Freshwater Ice

AbstractCrack propagation in columnar saline and freshwater ice has been investigated with high-speed photography, acoustic emission detection and the resistance method. High-speed photography was found to be a single reliable technique. The resistance method proved effective for freshwater ice samples, but not for saline ice samples due to the presence of conductive fluid inclusions. Acoustic emissions pinpointed the moment of crack initiation, but did not correspond to the crack propagation time. Crack velocity has been characterized over a temperature range of -5°C to -30 °C for freshwater and saline ice. Freshwater ice exhibited an overall average velocity of 198 m/s, and did not vary with temperature. Crack velocity in saline ice demonstrated temperature dependence, increasing from an average of 86 m/s in the -5°C to -20°C range, to 131 m/s at -30°C. The crack velocity was also shown to have a general dependence on fracture toughness K' of the material, however, the microstructural variation between samples is also shown to influence significantly the crack behavior in both saline and freshwater ice. Nonuniform crack tip advance and crack reorientation were observed as crack slowing mechanisms in freshwater ice, while in saline ice fracture crack tip blunting on voids greatly reduced average crack velocities.

Observation of crack propagation in saline ice and freshwater ice with fluid inclusion

2003 ◽  
Vol 81 (1-2) ◽  
pp. 159-166
Author(s):  
M Arakawa ◽  
V F Petrenko
Keyword(s):  
Crack Propagation ◽  
Electrical Resistance ◽  
Crack Velocity ◽  
High Speed ◽  
High Speed Photography ◽  
Low Density ◽  
Conductive Liquid ◽  
Freshwater Ice ◽  
Maximum Crack ◽  
Very High

A key process of crack propagation in saline ice is the interaction between the crack and fluid inclusions. We observed their interaction in freshwater ice using very high-speed photography (VHSP) and found that the low-density fluids (air and inert liquid, Fluorinert, 1.78 g/cm3) could not impede the crack effectively, interrupting the propagation for less than 10 µs. The high-density liquid mercury, (13.8 g/cm3) impeded the crack more effectively, stalling the development of the crack for more than 20 µs. The crack velocity in saline ice was measured using two different methods: electrical resistance method (ERM) and VHSP. These two methods returned very different mean velocities, 15 m/s for the ERM and 250 m/s for the VHSP. We found that in ice with conductive liquid inclusions, the ERM measured the time it took to break liquid bridges stretched across a crack rather than the crack velocity. Results from the VHSP show that the maximum crack velocity in saline ice was 500 m/s, which is one-half of that found in freshwater ice. From our results using freshwater ice with inclusions, we conclude that liquid inclusions in saline ice may play a role in this retardation. PACS No.: 62.20Mk

New crack generation phenomena by crack collision in 10 mm thick tempered glass

2021 ◽  
pp. 1-13
Author(s):  
Shin’ichi Aratani
Keyword(s):  
Tensile Stress ◽  
Crack Propagation ◽  
High Speed ◽  
Crack Tip ◽  
High Speed Photography ◽  
Tempered Glass ◽  
Crack Generation ◽  
Caustics Method ◽  
Thick Glass ◽  
Collision Angle

High speed photography by Caustics method using Cranz–Schardin camera was used to study crack propagation and divergence in thermally tempered glass. Tempered 10 mm thick glass plates were used as a specimen. New crack generation by two crack collision was observed. Regarding the presence/absence of new cracks, the dependence of the two cracks on the collision angle was confirmed. Considering that it is based on the synthesis of stress 𝜎CR generated at the crack tip, tensile stress necessary for the generation of new cracks could be created.

The Measurement of the Fatigue Crack-Tip Displacement and Strain Fields under High Frequency Resonant Loading Applying DIC Method

2015 ◽  
Vol 710 ◽  
pp. 83-90
Author(s):  
Hong Li Gao ◽  
Wei Jiang ◽  
Huan Liu ◽  
Huan Bin Zheng ◽  
Hui Liu
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
High Frequency ◽  
High Speed ◽  
Loading Condition ◽  
Crack Tip ◽  
Dynamic Strain ◽  
High Speed Photography ◽  
Stress Cycle ◽  
Strain Fields

In order to measure the displacement and strain field in the fatigue crack tip area of CT specimens under high frequency resonant loading condition in the fatigue crack propagation test, a method based on the digital image correlation (DIC) and digital high-speed photography technology are proposed in this paper. First, a series of digital speckle images of CT specimen under sinusoidal alternating load were collected by digital high-speed photography equipment, the displacement and strain fields within the region of crack tip in each image were calculated by DIC. The sinusoidal changing strain curve has been obtained by the least square sine wave fitting method, and the characteristic parameters of sinusoidal strain are calculated, such as the amplitude, frequency, phase, mean load . The images of characteristic position in one stress cycle were obtained by comparing the fitted sine curve of strain with the corresponding speckle images. Finally, the dynamic strain gauge was used to measure the strain at crack tip point during one stress cycle, and the accuracy and feasibility of DIC method were verified by the experimental results. The study result presented in this paper will supply a foundation for exploring the crack propagation law and measuring the fatigue crack growth parameters under high frequency resonant loading condition further.

scholarly journals Investigation on Dynamic Propagation Characteristics of In-Plane Cracks in PVB Laminated Glass Plates

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Xiaoqing Xu ◽  
Bohan Liu ◽  
Yibing Li
Keyword(s):  
Crack Propagation ◽  
Impact Loading ◽  
Crack Tip ◽  
Stress Waves ◽  
Critical Parameters ◽  
Propagation Mechanism ◽  
High Speed Photography ◽  
Laminated Glass ◽  
Propagation Characteristics ◽  
Crack Propagation Mechanism

Polyvinyl butyral (PVB) laminated glass has been widely used as an important component of mechanical and construction materials. Cracks on PVB laminated glass are rich in impact information, which contribute to its impact resistance design. In this paper, a three-dimensional (3D) numerical simulation model describing PVB laminated glass under impact loading is firstly established and validated qualitatively and quantitatively compared with the corresponding experimental results recorded by the high-speed photography system. In the meantime, the extended finite element method (XFEM) is introduced to analyze the crack propagation mechanism of laminated glass based on dynamic stress intensity factors (DSIFs) and propagations of stress waves. Parametric studies are then carried out to investigate the influence of five critical parameters, that is, plate dimension, crack length, impact energy, glass properties, and PVB properties, on crack propagation characteristics of laminated glass. Results show that the interaction between crack tip and stress waves as well as the propagations of stress waves corresponds to the fluctuations of DSIFs at crack tip. Both the structure and material variables are proven to play a very important role in glass cracking DSIFs and thus govern the crack propagation behavior. Results may provide fundamental explanation to the basic crack propagation mechanism on radial cracks in PVB laminated glass under impact loading conditions, thus to instruct its impact design improvement.

Experimental Study of Dynamic Fracture Behavior of PVB Laminated Glass by High-Speed Photography

2010 ◽  
Vol 34-35 ◽  
pp. 636-640 ◽  
Author(s):  
Meng Yi Zhu ◽  
Bo Han Liu ◽  
Yue Ting Sun ◽  
Jun Xu ◽  
Xue Feng Yao ◽  
...  
Keyword(s):  
Experimental Study ◽  
Finite Element ◽  
Dynamic Fracture ◽  
Crack Velocity ◽  
High Speed ◽  
Fracture Behavior ◽  
High Speed Photography ◽  
Laminated Glass ◽  
Fracture Characteristics ◽  
Photography Method

The dynamic fracture behavior of PVB laminated glass during impact has been studied by both theoretic and finite element approaches. To make the analysis of cracking on PVB laminated glass more accurate and direct, high-speed photography method is introduced in this paper. Different crack patterns as well as their sequences of appearance are visualized. Finally, typical crack is measured in order to obtain important fracture characteristics such as crack velocity and acceleration.

Micromechanical modeling of crack propagation in weak snow layer

2020 ◽  
Author(s):  
Gregoire Bobillier ◽  
Alec van Herwijnen ◽  
Bastian Bergfeld ◽  
Johan Gaume ◽  
Jürg Schweizer
Keyword(s):  
Mechanical Properties ◽  
Crack Propagation ◽  
Crack Velocity ◽  
Stress Component ◽  
Crack Tip ◽  
Micromechanical Modeling ◽  
Snow Layer ◽  
Mechanical Field ◽  
Fracture Dynamics ◽  
Micromechanical Approach

<p>Improving the prediction of snow avalanches requires a detailed understanding of the fracture behavior of snow, which is intimately linked to the mechanical properties of the snow layers (strength, elasticity of the weak and slab layer). While the basic concepts of avalanche release are conceptually relatively well understood, understanding crack propagation and fracture propensity remains a great challenge. About 15 years ago, the propagation saw test (PST) was developed. The PST is a fracture mechanical field test that provides information on crack propagation propensity in weak snowpack layers. It has become a valuable research tool to investigate processes and mechanical parameters involved in crack propagation.</p><p>Here, we use the discrete element method (DEM) to numerically simulate PST and therefore analyze fracture dynamics based on micromechanical approach. Using cohesive and non-cohesive ballistic deposition, we numerically reproduce the basic required layers for dry-snow avalanche: a highly porous and brittle weak layer covered by a dense cohesive slab.</p><p>The results of these numerical PTSs reproduce the main dynamics of crack propagation observed in the field. We developed different indicators to define the crack tip and therefore derive the crack velocity. Our results show that crack propagation on flat terrain reaches a stationary velocity if the snow column in long enough. The length of the snow column to reach stationary crack velocity depends on snowpack parameters. On sloped terrain our results show a transition in the local failure mode, this transition can be visualized from the crack tip morphology and from the main stress component.</p><p>Overall, our results lay the foundation for a comprehensive study on the influence of the snowpack mechanical properties on these fundamental processes for avalanche release.</p>

A Stress Intensity Factor Tracer

1985 ◽  
Vol 52 (2) ◽  
pp. 291-297 ◽  
Author(s):  
K.-S. Kim
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Focal Plane ◽  
High Speed ◽  
Focal Point ◽  
Crack Tip ◽  
Theoretical Development ◽  
Significant Feature ◽  
High Speed Photography

A new optical method, Stress Intensity Factor Tracer (SIFT), has been developed. The device measures continuously the real-time stress intensity factor variation, K1(t), of a moving crack tip using a single, stationary photodetector. The method uses the fact that any variation in K1(t) leads to a change in the intensity of light, I(t), impinging on a fixed finite area, Γ, on the focal plane. The focal plane is defined as the plane on which initially parallel light rays transmitted through a transparent fracture specimen (or reflected from the surface of an opaque specimen) are focused by a converging lens. Provided that the light detecting area, Γ, excludes the focal point, a simple relation, I(t) =B[K1(t)]4/3, has been obtained for a K1-dominant field. The constant, B, is a product of several experimental parameters including a “shape factor” of the sampling area, Γ, where I(t) is measured. A significant feature of this method is that I(t) is independent of the location of the crack tip in the illuminated zone on the specimen plane. The technique may therefore be applied to dynamic fracture studies without using high-speed photography. Only the constant, B, becomes a function of crack velocity for the dynamic K1-field. This paper presents the theoretical development of the SIFT method, including the wave optics of the system. Experimental results supporting the theory are included.

Indentation and Splitting of Freshwater Ice Floes

1995 ◽  
Vol 117 (1) ◽  
pp. 63-69
Author(s):  
D. S. Sodhi ◽  
S. N. Chin
Keyword(s):  
Crack Propagation ◽  
High Speed ◽  
Small Scale ◽  
Effective Pressure ◽  
Deformation And Failure ◽  
Low Speed ◽  
Freshwater Ice ◽  
Compressive Stresses ◽  
Ice Floes

Small-scale indentation and floe-splitting experiments were conducted on columnar ice floes of various sizes and at different speeds. During low-speed indentation (0.2–8 mm s−1), the ice floes always split apart, while at higher indentation speeds (> 100 mm s−1) they did not. The reason is attributed to differences in the process of deformation and failure. At low speed, a large zone of microcracked ice forms in front of the indentor. Development of compressive stresses in the microcracked ice zone leads to buildup of transverse forces that drive crack propagation. These zones of microcracked ice are not observed during high-speed indentation. Rather, the ice fails by continuous crushing. The theoretical effective pressure required to split an ice floe, as predicted by Bhat (1988), agrees to some extent with those measured during experiments.

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